Process for preparing olefin hydrocarbons for detergent use



United States Patent 3,402,217 PROCESS FOR PREPARING OLEFIN HYDRO CARBONS FOR DETERGENT USE Robert M. Engelbrecht, St. Louis, George D. Davis,

Creve Coeur, James M. Schuck, Webster Groves, Robert G. Schultz, Vinita Park, and Joseph Q. Snyder, St. Charles, Mo., assignors to Monsanto Company, St. Louis, Mo., a corporation of Delaware No Drawing. Filed Nov. 20, 1963, Ser. No. 325,156

. 9 Claims. (Cl. 260-683.15)

' The present invention relates to a process for the preparation of olefin hydrocarbons having particular utility in the preparation of detergent compositions The present invention also relates to a process for the preparation of alkyl aromatic compounds useful in the detergent industry. More particularly, the present invention relates to the preparation of olefin hydrocarbons and to their ultimate use in the production of alkyl aromatic compounds for detergent use, said alkyl aromatic compounds being susceptible to biological decomposition.

In this country, as well as in many foreign countries, the most extensively used of all synthetic detergents are the aromatic sulfonic acids. Of the aromatic sulfonic acid synthetic detergents, the most widely used and accepted are the alkylbenzene sulfonates. These detergent compounds combine relatively good detergent properties with relatively inexpensive production. The alkylbenzene sulfonates, to a large extent, derive their alkyl substituents from olefin polymers, with the most commonly used olefin polymers being propylene tetramers, pentamers, and fractions intermediate between these two. These propylene polymers are produced, generally, by the direct polymerization of propylene over phosphoric acid catalysts tothe tetramer, pentarner, etc.

. The alkylbenzene sulfonates derived from propylene tetramers, pentamers and fractions intermediate between these two, though having excellent detergent properties as well as being relatively inexpensive to manufacture, have in recent years begun creating a significant problem. These alkylbenzene sulfonates are highly resistant to biological oxidation, or, as otherwise known, biodegradation. Because of the resistance of these alkylbenzene sulfonate detergents to biological decomposition, considerable amounts of detergent compound pass through sewage or waste disposal plants unchanged. The presence of the undecomposed detergent in the effluent from these treat ing plants, where the efiluent is passed into streams, rivers or lakes, is responsible for unsightly nuisances in the form of foam and scum and represents potential toxicity hazards to aquatic life and to communities downstream. Further, the resistance of the presently known alkylbenzene sulfonates to decomposition causes considerable difiiculty in operating the sewage and waste disposal plants.

The problem of the resistance of present day alkyl aromatic sulfonates to biological decomposition is receiving rapidly increasing attention from public health officials, sanitary engineers and the detergent industry. In several countries of Europe the problem has become so acute as to inspire governmental action relative to the control of the manufacture of alkyl aromatic sulfonate detergents. Further, at the present time, several states in this country are seriously considering the problem created by the nonbiodegradable alkyl aromatic sulfonates.

The present invention has as one of its objects to provide a process for preparing alkyl aromatic compounds particularly suited for the preparation of detergent compositions susceptible to biological decomposition. Another object of the present invention is to provide a process for preparing biodegradable detergent compositions. A particular object of the present invention is to provide alkyl Patented Sept. 17 l9 6 8 aromatic sulfonate compositions and a process for their preparation which compositionsare susceptible to biological decomposition. Additional objects will become apparent from the following description of the vinvention herein disclosed.

The present invention comprises contacting in .a first polymerization zone at elevated temperatures andpressures normally gaseous mono-olefin hydrocarbons with a catalyst comprised of a molecular sieve and a metal from Group VIII of the Periodic Table, said catalysthaving been subjected to at least one oxidation treatment, to form a polymer fraction, separating said polymer fraction to obtain a fraction. comprised ofrelatively linear dimers of the normally gaseous mono-olefinhydrocarbons, said dimers having 4 to 8 carbon atoms, contacting said relatively linear dimer fraction in a second polymerization zone at a temperature of 50 to 250 C. and a pressure of atmospheric to 2500 p.s.i.g., with an activated carbon supported cobalt oxide catalyst activated at a temperature of 400 to 575 C. toform a second polymer fraction, separating said second polymer fraction to obtain a fraction comprised of relatively linear mono-olefin dimers of olefin hydrocarbons in the feed to the second polymerization zone, said dimers being of 8 to 16 carbon atoms. These relatively linear dimers of the second polymerization then may be reacted with an aromatic compound in the presence of an alkylation catalyst under alkylation conditions to form an alkyl aromatic compound and then the alkyl aromatic compound sulfonated and-subsequently neutralized. The alkyl aromatic sulfonate so produced is significantly more susceptible to biological decomposition than those prepared by presently known processes.

Molecular sieve as used herein refers to the crystalline zeolites, both naturally occurring and synthetic, which possess the characteristic of innumerable internal cavities with interconnecting channels and entrance pores into the internal cavities. As synthesized, the molecular sieve crystals contain water of hydration which on heating is driven out resulting in a geometric network of empty cavities which are connected by channels and open externally by means of pores. Molecular sieves are further characterized by uniformity in the diameters of the entrance pores. Entry pore diameters most generally vary in size from 3 to 15 angstroms, but any particular molecular sieve will possess pores of a substantially uniform diameter. The crystalline zeolites vary somewhat in composition, but generally contain the elements silicon, aluminum and oxygen as well as alkali and/or alkaline earth metal elements, e.g., sodium, potassium and/or calcium, magnesium and the like. The commercially available crystalline zeolites are generally synthetic sodium and/or calcium alumino-silicate crystals. Additional information regarding the composition of molecular sieve crystalline zeolites and their method of preparation is presented by Kimberlin and Mattox in US. Patent 2,972,643.

The term dimer as used herein refers to those polymers obtained by the condensation of two and only two molecules or monomer units of mono-olefinic hydrocarbons. These molecules or monomer units may be like or unlike. For example, dodecenes produced by the condensation of two hexene-l molecules or the condensation of a butene-l molecule and an octene-l molecule are equally within the meaning of the term dimer as used herein.

For purposes of simplifying the description of the present invention, the polymerization of normally gaseous mono-olefin hydrocarbons, briefly described above, will be hereinafter referred to as the first stage dimerization and the dimer product obtained from this first stage dimerization as the first stage dimer. The polymerization of the first stage dimer, also briefly described above, is hereinafter referred to as the second stage dimerization and 3 the dimer product obtained from this second stage dimerization as the second stage dimer.

Oxidation" as used herein includes the treatment of the catalyst in the presence of an oxygen containing gas under conditions which will generally bring about oxidation. The term oxidized state as used herein means merely that the catalyst has been subjected to oxidation as above defined and does not necessarily mean that which is in an oxidized state is an oxide. The term calcination as used herein refers to the initial oxidation treatment of the catalyst.

The catalyst used in the first stage dimerization is one comprised of a molecular sieve crystalline zeolite containing an element from Group VIII of the Periodic Table. The crystalline zeolites which may be used in the present invention include both natural and synthetic zeolites. Description of such zeolites is found in the prior patent art as well as in the literature. Zeolites, both natural and synthetic, vary considerably in composition, but most generally contain silicon, aluminum, oxygen, and an alkali and/or alkaline earth metal element or elements. In the preferred practice of the present invention the zeolite may be either natural or synthetic, but will have surface areas of 200 to 1200 square meters per gram and pore diameters of 6 to angstroms and are those which contain the elements silicon, aluminum, oxygen, and an alkali and/or alkaline earth metal element. The preferred crystalline zeolites of the present invention are those containing silicon, aluminum, oxygen and sodium and/or potassium, and/or calcium, and/or magnesium. These preferred crystalline zeolites will have surface areas within the ranges described above, but will have pore diameters of 8 to 13 angstroms. The particularly preferred crystalline zeolites of the present invention are those containing sodium or potassium and silicon, aluminum and oxygen. The Group VIII metals useful in the present invention are all of these included within this group of the vPeriodic Table which includes iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, and platinum. It is believed that the Group VIII metal is present in the molecular sieve in the form of an oxide of the metal. However, since this is presently undetermined the present invention is not to be limited to a catalyst containing a Group VIII metal oxide. For the sake of description, the Group VIII metal will be described as being in an oxidized state which for the purposes of the present invention means simply that it has been subjected to an oxidation type treatment. The preferred Group VIII metals of the present invention are nickel and cobalt with nickel being somewhat preferred over cobalt. The amount of the Group VIII metal present within the molecular sieve crystalline zeolite will generally range from approximately 0.2 to 15 percent by weight, calculated as an oxide of the Group VIII metal, of the total catalyst. It will, however, be preferred that the amount of Group VIII metal present in the catalyst be within the range of approximately 0.5 to 10 percent by weight, calculated as an oxide of the Group VIII metal, of the total catalyst. For the optimum in results with the preferred feedstocks and conditions of the present process, it will generally be preferred to have a catalyst containing approximately 0.5 to 7 percent by weight of the Group VIII metal, calculated as its oxide. Throughout this application, the term within the molecular sieve is used in referring to the location of the Group VIII metal. This term for the purposes of the present specification means that the Group VIII metal is dispersed within the intercrystalline cavities of the molecular sieve either as a surface dispersion or as being ion-exchanged into the structure of the molecular sieve.

The method of placing the Group VIII metal within the intercrystalline cavities of the molecular sieve is not particularly critical to the present invention. The metal may be placed within the molecular sieve either by total 4 immersion, thereby causing ion-exchange of the metal into the structure of the molecular sieve, or by just moistening or wetting, which it is believed brings about a surface deposition of the metal within the intercrystalline cavities rather than ion-exchange into the structure of the molecular sieve. After the Group VIII metal has been placed within the intercrystalline cavities subsequent treatment of the catalyst becomes somewhat critical. The catalyst is subjected to calcination in the presence of air or other oxygen containing gases at an elevated temperature. Preferably this calcination or oxidation treatment, the two terms being used interchangeably for the purpose of the present description, will be carried out at a temperature of approximately 300 to 600 C. In the preferred embodiment of the present invention, after this initial oxidation treatment or calcination, the catalyst is subjected to reduction in the presence of a reducing gas at an elevated temperature and thereafter subjected to a second oxidation treatment in the presence of air or other oxygen containing gas also at an elevated temperature. In this preferred embodiment, it is somewhat preferred that the reduction temperature be within the range of 50 to 550 C. and the second oxidation treatment carried out within the range of 25 to 550 C. The calcination or oxidation atmosphere may be any of the known oxidation gases. Generally, air, oxygen or mixtures thereof will be used for the oxidation treatment. When the catalyst is subjected to reduction as an intermediate step, any of the known reducing gases may be used. Generally, hydrogen will be preferred.

The temperature at which the first stage dimerization reaction of the present invention is carried out is generally within the range of from as low as 60 C. to as high as 350 C. Generally, it is necessary for initiation of the polymerization reaction to attain a temperature in excess of 145 C. However, once polymerization is initiated the temperature generally may, if desired, be lowered considerably within the above range. The preferred temperatures for operating the first stage dimerization are within the range of to 235 C. Generally it is desired to operate near the lower limit of the above ranges. The effect of temperature is to increase total conversion to polymer as temperature is increased and to bring about a decrease in the a mout of dimer product produced. Therefore, a balance between total conversion and dimer product is desirable. Such a balance may be obtained within the above cited temperature ranges. The first stage dimerization is operable at pressures ranging from atmospheric pressure or approximately atmospheric pressure, i.e., 5 to 10 p.s.i.g., up to 1000 p.s.i.g. Generall-y, however, it is preferred to operate the first stage dimerization within the pressure range of 300 to 700 p.s.rg.

The conversion of the normally gaseous mono-olefin hydrocarbons to dimer in the first stage dimerization is dependent upon the space velocity of the olefins in the first stage. From a practical standpoint the space velocities will be maintained within the range of from approximately 0.2 to 5.0 parts by weight of hydrocarbon feed per hour per part by weight of catalyst. A preferred space velocity, however, is within the range of from 0.5 to 2.0 parts by weight of hydrocarbon feed per hour per part by weight of catalyst. The dimerization of normally gaseous mono-olefin hydrocarbons in the presence of catalysts comprised of molecular sieves containing a Group VIII metal is disclosed and claimed in copending application Ser. No. 232.857. filed Oct. 24. 1962. now abandoned.

The first stage dimerization of the present process dimerizes normally gaseous mono-olefin hydrocarbons. The normally gaseous mono-olefin hydrocarbons are ethylene, propylene and butylenes. The feed to the first stage dimerization may contain only one of these mono-olefins or it may contain a mixture of two or more. When two or more of these mono-olefins are present both dimerization and codimerization will take place. For example, if

the feed comprises ethylene and propylene, then ethylene dimers of 4 carbon atoms and propylene dimers of 6 carbon atoms will be formed as well as ethylenepropylene codimers of 5 carbon atoms. If the normally gaseous mono-olefin feed includes butylenes, it is usually preferred that the butylenes be n-butylenes. Further, it is preferred that the n-butylene be terminally unsaturated. The preferred feed to the first stage dimerization is propylene. Though it is generally preferred to have a relatively pure normally gaseous mono-olefin hydrocarbon feed to the first stage dimerization, it is not altogether necessary. The feed may contain small amounts of mono-olefins other than the normally gaseous monoolefins. However, since the primary purpose of the first stage dimerization is to produce dimers of 4 to 8 carbon atoms, the amount of other polymerizable mono-olefins present in the feed should be kept to a minimum. The presence of diolefins and triolefins as well as acetylenic compounds in the feed is to be avoided since these materials poison the catalyst to some extent. However, from a practical standpoint small amounts of such materials, below approximately 0.02 percent by weight of the feed may be tolerated. Saturated hydrocarbons as well as other inert materials may be present in the feed to a considerable extent. Such materials have no deleterious effect on the dimerization reaction. However, as a practical matter, large quantities of these materials are to be avoided since they are merely dead weight" to the process and needlessly increase the cost of handling the feed materials and products.

The method by which the hydrocarbon feed is contacted with the catalyst may be practically any method known to the art. The process may be one involving gassolid or liquid-solid contact. The zeolite catalyst bed may be stationary or fluidized. If fluidized, the zeolite may be in the form of dry powder or pellets or may be slurried in an appropriate liquid. The arrangement and design of the apparatus is not particularly critical to the present process so long as good engineering principles are followed.

- A particularly preferred embodiment of the first stage dimerization is one in which normally gaseous monoolefin hydrocarbons, preferably propylene, are contacted at elevated temperatures and pressures with the catalyst which comprises a molecular sieve and a metal from Group VIII of the Periodic Table, said metal containing molecular sieves having been subjected to an oxidation treatment or calcination in the presence of an oxygen containing gas followed by reduction and then a second oxidation treatment.

The feeds to the second stage dimerization reaction are the relatively linear mono-olefinic dimer products of the first stage dimerization. These dimer products are of 4 to 8 carbon atoms depending upon the normally gaseous mono-olefin hydrocarbons in the feed to the first stage dimerization. If the preferred normally gaseous monoolefin hydrocarbon, propylene, is the feed to the first stage dimerization, then the dimer feed to the second stage dimerization is ordinarily of 6 carbon atoms. It is preferred that the dimer feed to the second stage dimeriza tion be substantially linear mono-olefin hydrocarbons. However, the presence of branched-chain mono-olefins up to a concentration of 15 percent by weight of the feed to the second stage dimerization is not deleterious to the present invention. A particulgrly preferred mono-olefin dimer feed to the second stage dimerization is one which contains no greater than 10 percent by weight of branchedchain mono-olefin hydrocarbons with the remainder of the mono-olefins being straight-chain. The mono-olefin hydrocarbons in the feed to the second stage dimerization include both internally and terminally unsaturated mono-olefin hydrocarbons. Since the feed to the second stage dimerization is a product of the first stage dimerization, there Will generally be fewer impurities such as diolefins, triolefins, saturated hydrocarbons, inert materials and the like than are in the feed to the first stage dimerization. Further, since in most instances the product from the first stage dimerization is subjected to a separation step to recover the dimers produced and to exclude excess branched-chain mono-olefins, most of the impurities such as those above mentioned may, if present, also be re moved during this separation step. I

The separation step used for purifying the product of the first stage dimerization to meet the above discussed feed requirements of the second stage dimerization may be carried out by any conventional means. Generally, ordinary fractional distillation will be adequate for effecting the purification of the dimer product of. the first stage dimerization. The determination of the precise fractionation equipment and conditions for obtaining the second stage dimerization feed, is well within the ability of those skilled in the art having the above definition of this feed before them. When the preferred feed, propylene, is dimerized in the first stage dimerization, fractionation of the dimer product to obtain an overhead fraction having a boiling range of approximately 60 to C. will usually provide a suitable feed for the second stage dimerization. In addition to or in place of fractional distillation, other conventional separation or purification means such as adsorbents, i.e., molecular sieves, solvent extraction, extractive distillation, selective polymerization, isomerization and the like may be employed to conform the dimer product of the first stage dimerization to the feed requirements of the second stage dimerization. To repeat, it is immaterial to the present invention what separation means is used for purifying the product of the first stage dimerization to meet the feed requirements of the second stage dimerization, so long as'such separation means provides the desired purification.

One of the primary advantages found in the herein disclosed first stage dimerization process is found in its production of relatively large quantities of dimers meeting the above defined feed requirements to the second stage dimerization. The amount of second stage dimerization feedstock produced by the first stage dimerization is significantly improved over other conventional processes. To meet the above defined second stage feed requirements, it is generally necessary to remove a portion of the branched-chain dimers by -such means ,as fractionation. Many of the isomeric branched-chain dimers are exceptionally diificult 'to separate from the straightchain dimers by ordinary separation means such as fractionation. The first stage dimerization process of the pres ent invention produces significantly less of these difficultly separable branched-chain isomers than do other known polymerization processes.

The base supports useful in the catalyst used in the second stage dimerization are activated carbons. These activated carbons may be any porous carbon known to be useful for catalyst preparation. The activated carbons generally have surface areas of about 400 to 2000 square meters per gram and may be in the form of compact masses, granules, chips, powders, etc. Suitable supports include coconut charcoal, wood charcoal, carbon derived from coke, soft bone charcoal, hard bone charcoal, and the like. The activated carbon may be obtained from animal, vegetable or petroleum sources and may include such commercial materials as Pittsburgh BPL, CAL, 0L, and SGL produced by Pittsburgh Coke and Chemical Co., Girdler G32C, and G-32-E produced by Chemical Products Division, Chemetron Corp.,

and Barnebey-Cheney Companys BE-1 and E-H-l.

In preparing the activated carbon supported second stage dimerization catalyst, an activated carbon is impregnated with a solution of a cobalt salt and the salt subsequently converted to the oxide. This treatment of the activated carbon may be carried out by immersion of the carbon. in the cobalt salt solution by just moistening the carbon with the cobalt salt solution or by any other means known to those skilled in the art for impregnation of catalyst supports. The cobalt salt solution consists of a cobalt salt dissolved in any suitable solvent for the cobalt salt. Generally, wherever practical, aqueous or alcoholic solutions of the cobalt salt are used. Among the cobalt salts useful for impregnation of the activated carbon are the following non-limiting examples: Cobalt acetate, cobalt sulfate, cobalt nitrate, cobalt butanoate, cobalt pentanoate, cobalt hexanoate, cobalt ammonium sulfate, cobalt arsenate, cobalt arsenite, cobalt carbonate, cobalt chromate, cobalt vandate, cobalt molybdate, cobalt iodate, cobalt oxalate, cobalt citrate, cobalt sulfite and the like. The most useful cobalt salts are cobalt acetate, cobalt sulfate and cobalt nitrate'in the cobaltous form with cobalt nitrate being the preferred salt. The cobalt salt solution is preferably an aqueous solution having a concentration calculated to give the desired amount of cobalt oxide on the activated carbon after activation of the catalyst.

Prior to treatment of the activated carbon with the cobalt salt solution, it is often preferred to pretreat the activated carbon to improve its efiicacy. This pretreatment may take the form of an acid wash which, though not necessary, is a frequently desired pretreatment of activated carbons. If acid washed, it is preferred that the acid be an aqueous nitric acid. This aqueous nitric acid is preferably used in an amount of approximately 600 to 1000 mls. of acid per 500 mls. of activated carbon. It is generally preferred that the nitric acid be of a concentration of about to 30 percent in water though it may be of virtually any concentration. The acid wash, When used, ordinarily will be from 2 to 10 minutes in duration with 3 to 5 minutes generally being sufficient. After acid washing, the activated carbon is washed with water and if desired, dried.

In addition to or in place of acid washing, it is in many instances preferred to pretreat the activated carbon with a nonoxidizing gas or liquid. Usually, it is preferred that the activated carbon be dried previous to this form of treat-ment. When treating the activated carlon with a nonoxidising gas, the gas is merely passed over the activated carbon, generally, at a temperature of 150 to 500 C. for 0.5 to 8 hours. It is preferred that the non-oxidising gas be passed over the activated carbon at a temperature of 200 to 350 C. for 1 to 2 hours. The nonoxidizing gases include such gases as hydrogen, nitrogen, ammonia, helium, argon, and the like. These nonoxidizing gases may be used alone or in combination. It is preferred that the nonoxidizing gas, if used, be one selected from the group consisting of hydrogen, nitrogen, ammonia and combinations thereof with ammonia being preferred over the others. The nonoxidizing gases, when used, will generally be in the gaseous state; however, it is within the scope of the present invention to use the nonoxidizing gases in a liquefied form. Thus, in referring to these nonoxidizing gases as gases, it is meant that they are normally gaseous and not that they are limited to utilization in the gaseous form.

Among the nonoxidizing liquids which may be utilized in this pretreatment of the activated carbon are such compounds as ammonium hydroxide and the like. In most instances, the preferred nonoxidizing liquid is ammonium hydroxide. The nonoxidizing liquid is used in practically any concentration and the treatment carried out by immersing the dried activated carbon in the nonoxidizing liquid for a time sufiicient for complete adsorption by the activated carbon of the maximum amount of the liquid adsorbable by the carbon. In using the preferred nonoxidizing liquid, ammonium hydroxide, concentrations of to percent by weight in water preferably will be used. Generally, treatment of the activated carbon with a non-oxidizing liquid is at ambient temperatures (20 to C.) though both higher and lower temperatures may be used.

The particularly preferred manner of treating the activated carbon prior to impregnation with cobalt salt is referred to as ammoniation and consists of pretreating the carbon with either ammonia or ammonium hydroxide or a combination thereof as described in the preceding paragraph. When both ammonia and ammonium hydroxide are used it is immaterial whether one or the other is used first followed by the other or whether they are used simultaneously.

The use of non-oxidizing gases and liquids in the treatment of activated carbon supported cobalt oxide catalysts is fully disclosed and claimed in copending applications Ser. No. 294,750, Filed July 12, 1963, now US. Patent No. 3,317,628, Ser. No. 229,192, Filed Oct. 8, 1962, now abandoned, and Ser. No. 254,433, Filed Jan. 28, 1963, now US. Patent No. 3,333,016.

Though not necessary, it generally is desirable to have the activated carbon dry before it is treated with the cobalt salt solution. A particularly useful, but by no means limiting, manner of drying the activated carbon comprises heating the activated carbon at a temperature of 50 to 200 C. for 2 to 24 hours. A preferred method of drying the activated carbon comprises maintaining the carbon at a temperature of to C. for 2 to 6 hours. To facilitate drying, reduced pressures may be used. Of course, reduced pressures will shorten the drying period and/or lower the temperatures.

After the activated carbon has been impregnated with the cobalt salt solution, the impregnated activated carbon is again subjected to a drying treatment. This drying treatment is carried out in the manner described in the preceding paragraph. It is not absolutely necessary that the catalyst be completely dried prior to activation. However, caution should be exercised in activating a catalyst which has not been subjected to at least partial drying. The drying step after impregnation brings about decomposition of the cobalt salt. Thus, if the catalyst has not been subjected to drying, there is a distinct possibility of overly rapid decomposition resulting in an explosion when the catalyst is subjected to activation.

Upon completion of the impregnation of the activated carbon with the cobalt salt, it is in some instances desirable, prior to activation, to subject the catalyst to treatment with a nonoxidizing gas or liquid such as ammonia, ammonium hydroxide or a combination thereof. This treatment of the cobalt salt impregnated carbon with a nonoxidizing gas or liquid is carried out in the same manner and under the same conditions as is the treatment of the activated carbon alone with a nonoxidizing gas or liquid which has been hereinabove described. The treatment of the cobalt salt impregnated activated carbon with a nonoxidizing gas or liquid may be in addition to or instead of the pretreatment of the activated carbon prior to impregnation. The treatment of either the activated carbon or the cobalt salt impregnated activated carbon with the nonoxidizing gases and liquids is not necessary to the present invention and is not to be construed as limiting the present invention. This treatment merely reflects one of several modes of practice of the present invention.

The most critical feature in the preparation of the activated carbon supported cobalt oxide catalyst of the second stage dimerization is found in the activation of the catalyst. Activation is most often carried out at temperatures within the range of 400 to 575 C. with temperatures of 425 to 525 C. being preferred. Generally, a period of 0.5 to 3 hours is sufficient for complete activation of the catalyst. The catalyst activation is carried out in the presence of an inert atmosphere, i.e., helium, argon, carbon dioxide, nitrogen and the like. Generally, it is preferred to use nitrogen as the inert atmosphere. Activation may be carried out at slightly reduced pressures if desired. If reduced pressures are used, it is preferred that the pressures not be reduced below 10 mm. Hg though lower pressures may be used if desired.

Another feature of some importance in the second stage dimerization catalyst is the amount of cobalt present as cobalt oxide on the finished catalyst. A second stage dimerization catalyst may contain 2 to 50 percent by weight and higher of cobalt as an oxide. Generally, it is somewhat preferable to use a catalyst having the cobalt concentration as the oxide within a range of 5 to 30 percent by weight of the total catalyst. for optimum dimerization activity in the second stage, the cobalt, as cobalt oxide, is present in the catalyst in an amount equivalent to 12 to 30 percent by weight of the finished catalyst.

The dimerization temperatures used in the second dimerization generally are within the range of from approximately to 250 C. Usually, however, the second stage dimerization temperature is 100 to 200 C. Preferred temperatures for the second stage dimerization are within the range of approximately 125 to 200 C. Dimerization pressures in the second stage dimerization usually are within the range of from atmospheric pressure to 2500 p.s.i.g. and higher. More often, however, pressures for the second stage dimerization are within the range of from approximately 10 to 400 p.s.i.g. with pressures of 100 to 30 0 p.s.i.g. preferred. The space Velocity of the feed material in the catalyst zone of the second stage dimerization usually is within the range of 0.1 to 50 liquid volumes of feed per hour per volume of catalyst. Preferred space velocities for the second stage dimerization are within the range of from approximately 0.1 to 5 liquid volumes of feed per hour per volume of catalyst.

The polymer product obtained from the second stage dimerization is comprised of unreacted dimers of the second stage feed mono-olefins and also some higher molecular weight polymers. This polymer product is subjected to fractional distillation or to some other separation means to recover the total dimer fraction from the unpolymerized feed material and the polymers of higher molecular weight than dimers, i.c., trimers, tetramers, etc. The dimer product of this second stage dimerization is relatively linear in character, generally containing 90 to 95 percent by weight of dimers which are straight-chained or branched-chain containing a single branched substituent. These dimers have the saturated general formula.

Ra Rr-C-(il-C-C-R: wherein the total number of carbon atoms is 8 to 16 and wherein R and R may be hydrogen or a n-alkyl hydrocarbon group of 4 to 12 carbon atoms and R may be hydrogen or a n-alkyl hydrocarbon group selected from the group consisting of methyl, ethyl and propyl.

The particularly preferred dimer product of the second stage dimerization is one in which the dimers are of 12 carbon atoms and which is comprised of 15 to 55 percent by weight of methyl undecanes and 25 to 85 percent by weight of n-dodecenes. This preferred product is generally obtained by using propylene as the feed to the first stage dimerization and then recovering from the first stage dimerization product the hereinabove discussed and defined preferred feed to the second stage dimerization.

One of the primary advantages of the present invention is that the total dimer product of the second stage dimerization is relatively linear and as such may be used in total without additional separation steps in the preparation of alkyl aromatic sulfonates which are substantially biodegradable. Also, this second stage dimer fraction finds utility in many other uses requiring relatively linear mono-olefins.

The method whereby the product obtained from the second stage dimerization is separated to obtain the dimer fraction is not critical to the present invention. Practically any method of separation may be used. It is only necessary that the separation means be such as to separate relatively linear dimer fraction from the unpolymerized olefins of the feed and the polymers higher in molecular weight than the dimers.

After the relatively linear dimer fraction is obtained from the second stage dimerization, it is then reacted under alkylation conditions with an aromatic compound to form an alkyl aromatic compound. This alkylation reaction may be carried out by any of the methods known to the art. The process by which alkylation of the aromatic compound with the relatively linear dimer is carried out may include those using such catalysts as the Friedel-Crafts type catalysts such as AlCl GaCl FeCl BF TiCl SnCI ZnCl and the like as well as such other alkylation catalysts as HF, H 50 H PO on kieselguhr. Alkylation in the presence of Friedel-Crafts type catalysts will most often be carried out in the presence of a hydrogen halide, i.e., HCl, HB'r, HI, HF. The catalyst and hydrogen halide will usually be present in a weight ratio of 2:1 to 1:2. The alkylation also may be carried out by purely thermal alkylation means. Alkylation conditions include temperatures ranging from 0 to 425 C. and with, of course, higher temperatures being necessary for thermal alkylation. Also, elevated pressures may be utilized, especially in thermal alkylation which often uses pressures in excess of 1000 p.s.i.g. Of course, the amount of catalyst, as well as the relative amounts of aromatic and dimer fraction, will vary considerably depending on catalyst and process conditions. Preferably, the mol ratio of dimer fraction to aromatics will be 0.5 :1 to 5:1 though other ratios may be used. A very practical and somewhat preferred manner of carrying out the alkylation of the aromatic compounds is that illustrated by the example hereinafter presented. Briefly described, this preferred mode of alkylating the aromatic compound with the second stage dimer comprises subjecting the dimer and aromatic compound in a mol ratio of 1:6 to a temperature of 30 to 35 C. for 30 to 60 minutes in the presence of a Friedel-Crafts type catalyst, particularly aluminum chloride, and a hydrogen halide, preferably HCl, the ratio of catalyst to hydrogen halide being 1:1. It is, of course, understood that this merely represents a preferred and practical method of alkylation and is in no manner to be construed as limiting the present invention.

The aromatic compounds which may be alkylated with the monolefin dimer fraction in the practice of the present invention includes any of the aromatic compounds known and conventionally utilized in the preparation of detergent compositions. These aromatic compounds include aromatic hydrocarbons, both monoand poly-nuclear. The aromatic hydrocarbons are both substituted and unsubstituted aromatics. When substituted, the aromatic nucleus may have any number of substituents, though it is usually preferred that there be no more than two substituents already on the aromatic nucleus. The substituents to the aromatic nucleus may be any substituent which will not appreciably interfere 'with the surface activity of the finished alkyl aromatic sulfonate. Generally, it is preferred that the aromatic nucleus have no more than two alkyl substituents and that these substituents have no more than 3 carbon atoms per substituent. Among the aromatic hydrocarbons which may be alkylated with the mono-olefin dimer fraction in the preparation of biodegradable alkyl aromatic sulfonates for detergent use are the following nonlimiting examples: benzene, toluene, ethylbenzene, xylenes, iso-propyl ben- Zene, n-butyl benzene, diethylbenzenes, naphthalene, meth ylnaphthalenes, dimethylnaphthalenes, ethylnaphthalenes, diethylnaphthalenes, diphenyl, methyldiphenyl, dimethyldiphenyls, ethyldiphenyls, anthracene, phenanthrene, methylphenanthrene, methylanthracene, dimethylanthracene, diethylphenanthrene and the like. The particularly preferred aromatic hydrocarbons for the purposes of the present invention are benzene, toluene, naphthalene and methylnaphthalenes. In addition to the aromatic hydrocarbons, such other aromatic compounds as those in the following nonlimiting list may be made to produce more biodegradable detergents by incorporation thereon of the present mono-olefin dimer fraction as an alkyl substituent.

These aromatic compounds include phenols, cresols, xylenols, lower alkylated phenols, phenol others, diaryl ethers, naphthols, naphthol ethers, phenyl phenols, and the like.

The sulfonation of the alkyl aromatic hydrocarbon may be accomplished by any number of methods. Useful methods include those wherein the sulfonating agents are sulfuric acid, anhydrous sulfur trioxide, chloro-sulfonic acid or such special reagents as sulfuric acid, acetic acid anhydride, sulfur trioxide-pyridine, sulfur trioxide-dioxane and the like. Generally, it would be preferred to use sulfuric acid of a strength of to 80 percent. The sulfonating agents generally are used in a molar equivalent to the alkyl aromatics being sulfonated. However, if desired, an excess of sulfonating agent may be used. Sulfonation may be carried out at temperatures ranging from C. and lower up to 60 C. and higher. After sulfonation is complete, the product is neutralized with an alkali. A very practical and somewhat preferred method of sulfonating the alkyl aromatic compound is that illustrated by the example hereinafter presented. This somewhat preferred method comprises treating the alkyl aromatic compound for 5 to 7 minutes with 20 percent oleum at a temperature of 47 to 53 C. while maintaining vigorous agitation, thereafter lowering the temperature to 37 to 43 C. for about to minutes and adding water and subsequently recovering the sulfonic acid layer and thereafter neutralizing with an alkali solution, particularly sodium hydroxide. This method is only a preferred method and is in no manner limiting to the present invention.

In order to further describe and to illustrate the present invention, the following examples are presented. These examples are in no way to be construed as limiting the present invention.

EXAMPLE I To a solution of nickel chloride prepared from approximately 35.9 grams of NiCl -6H O and 1000 grams of H 0 was added approximately 295 grams of a molecular sieve in the form of inch cylindrical pellets. The molecular sieve was a sodium-alumino-silicate having intercrystalline cavities and external pores of 10 angstroms and which is known commercially as Linde Type 13X molecular sieve. The resulting mixture was mildly agitated and then allowed to stand for approximately 24 hours at a temperature of from 25 to 40 C. After this period, the molecular sieve was recovered from the solution by decantation, thoroughly water washed and then dried for several hours at a temperature of 120 to 130 C. Next, the ionexchanged molecular sieve was calcined by passing air over the catalyst at a temperature of 550 C. at a velocity of 25 liters/hr. for approximately 24 hours. The catalyst was then reduced by passing a hydrogen steam over the catalyst for approximately 16 hours at a velocity of 20 liters/hr. and a temperature of 270 to 330 C. After reduction, the molecular sieve catalyst was subjected to oxidation at an air velocity of 20 liters/hr. for six hours at a temperature of 350 to 440 C. The molecular sieve catalyst so prepared contained approximately 3 percent by weight nickel calculated as nickel oxide.

Approximately grams of the above prepared catalyst was placed in a 1 inch diameter stainless steel cylinder 8 inches in length and a propylene feed comprised of 80 weight percent propylene and 20 weight percent propane was then placed into contact with the catalyst at a space velocity of 1.25 grams of feed per gram of catalyst per hour. It was necessary to raise the temperature in excess of 140 C. in order to initiate polymerization. However, as soon as polymerization began the temperatures were adjusted to approximately 90 C. for the remainder of the run. The pressure within the reaction zone was maintained at approximately 600 p.s.i.g. A product was obtained of which 20 weight percent was liquid product, of which 96 weight percent was propylene dimer. The propylene dimer was found to contain approximately 56 weight percent linear dimers.

The polymer fraction is next subjected to fractionation from which a dimer fraction having a boiling range of approximately 61 to C. is obtained. This dimer fraction has the following composition.

Component Weight percent Straight-chain mono-olefin dimer 85.3 Branched-chain mono-olefin dimer 14.7

This dimer fraction represents the feedstock to the second stage dimerization.

A second catalyst was prepared by adding approximately 300 mls. of concentrated ammonium hydroxide to approximately 300 grams of a commercial grade (BPL) of activated carbon. All of the ammonium hydroxide was adsorbed. The ammonium hydroxide treated activated carbon was dried for approximately two hours at about 130 C. Next, the dried carbon was immersed in a solution of approximately 200 grams of cobalt nitrate hexahydrate in 250 mls. of demineralized water. The cobalt nitrate impregnated carbon was then dried at a low heat for approximately 3 hours until there was no visible liquid or water on the carbon and placed under vacuum for about 18 hours at a temperature of 120 C. The dried cobalt nitrate impregnated carbon was immersed in about 500 mls. of concentrated ammonium hydroxide which was rapidly adsorbed. This catalyst was then dried to visible dryness and placed under vacuum at 120 C. for 25 hours. As a final step, the catalyst was activated by heating at a temperature of 475 C. in the presence of a nitrogen flow for 2 hours. This catalyst contained approximately 13.5 percent by weight of cobalt, calculated as cobalt oxide.

Approximately 56.2 grams of this catalyst were placed in a reactor one inch in diameter, 4 inches long. Approximately 3,926 grams of the fraction of the composition as set out above was passed through this catalyst bed at a rate of 0.67 mls. per minute. The catalyst bed was maintained at a temperature of approximately 150 C. and at a pressure of approximately 300 p.s.i.g. The polymer fraction recovered was subjected to distillation and approximately 251 grams of dodecenes were obtained.

Alkylation was carried out by placing approximately 175.5 grams of dry benzene in a cylindrical glass reactor equipped with a cooling coil thermometer well and means for agitation. Next, anhydrous hydrogen chloride was bubbled into the reactor for approximately 7 minutes. To this mixture was added approximately 3.2 grams of anhydrous aluminum chloride. Next, approximately grams of the above described C dimer fraction was added over a period of 15 minutes to the benzene-catalyst mixture. Continuous agitation was maintained throughout the addition of the olefin material and the temperature was maintained between 30-35 C. throughout this period. After completion of the addition of the olefin, the reaction mass was allowed to age for approximately 15 minutes. The alkylation mass was then allowed to settle without agitation for one hour and the lower catalyst complex layer separated from the reaction mass. The remaining alkylated liquor was then washed with an equal volume of tap water.

Approximately 259 grams of the washed alkylated liquor was distilled batchwise through a /2 inch diameter packed column 12 inches in height. Benzene was recovered at atmospheric pressure at a 1:1 reflux ratio from the distillation. After removal of the benzene, the distillation was continued under reduced pressure. The alkylbenzene product fraction was obtained within the boiling range of 123 C. to 135 C. at 2 mm. Hg. Approximately 83.7 grams of a'lkylbenzene was recovered.

Approximately 75 grams of the distilled alkylbenzenes were charged to a 250 ml. flask. To this was added approximately grams of 20 percent oleum. The oleum was added over a 6 minute period while maintaining vigorous agitation and while maintaining a temperature of 50i-3 C. After the addition of the oleum was complete the temperature was lowered to 40i3 C. and held for approximately 45 minutes. To this mixture was then added approximately 16.5 mls. of distilled water at such a rate that the temperature of the mixture could be held below 65 C. After the water was added, alkylation was stopped and the sulfonation mass transferred to a centrifuge tube and centrifuged for 30 minutes. The lower spent acid layer was separated and the sulfonic acid layer dissolved in 750 mls. of 80 percent isopropanol. The solution was then neutralized to a pH of 7.0 to 9.0 with a 25 percent sodium hydroxide solution. The resultant mixture was filtered to remove solid Na SO and the remaining solution dried to obtain alkylbenzene sulfonate.

EXAMPLE II In order to demonstrate the efiicacy of the present invention the alkylbenzene sulfonate prepared in accordance with the present invention is compared in biodegradability with a conventional alkylbenzene sulfonate. The conventional alkylbenzene sulfonate used as a standard is that most extensively used in present day detergents which is an alkylbenzene sulfonate prepared from propylene tetramer. The propylene tetramer is obtained by the commonly used process for polymerizing propylene which is the polymerization of propylene over a phosphoric acid catalyst as set out in US. Patent No. 2,075,- 433. The method for preparing an alkylbenzene sulfonate from the tetramer is substantially the same as the alkylation and sulfonation procedures set out above. In comparing the conventionally prepared propylene tetramer derived alkylbenzene sulfonates with an alkylbenzene sulfonate prepared in accordance with the present invention, the activated sludge test is used. This test is carried out by contacting the test compounds with a sludge obtained from an activated sludge sewage disposal plant in the following manner. Approximately 1500 mls. of the sludge is maintained at room temperature and normal room lighting conditions in a 2 liter graduate while under constant agitation by a stream of air introduced near the bottom of the graduate for approximately 23 hours. The sludge is allowed to settle for one hour and then 1000- mls. of the supernatant liquor is withdrawn and replaced by one liter of tap water containing 25 milligrams of test compound, 150 mgs. of glucose, 159 mgs. of nutrient broth, 150 mgs. of sodium benzoate, 150 mgs. dipotassium hydrogen phosphate and 25 mgs. of ammonium sulfate. The aeration is then continued for the next 23 hours and once more allowed to settle and then 1000 mls. of the supernatant liquid decanted. The decanted liquid is analyzed for test compound by the Longwell-Maniece modification of 'the methylene blue method as described in The Analyst, vol. 62, 826-827 (1957). The amount of test alkylbenzene sulfonate in the. decanted efiiuent is subtracted from the amount initially added to obtain the amount of test material which had biodegraded. From this the percent biodegradation of the test compounds is obtained. For greater accuracy in this procedure, the tests are repeated over and over until a constant percent biodegradation is obtained for each test compound. The results of the tests are given in the following table wherein alkylbenzene sulfonate A is one prepared in accordance with the present invention and alkylbenzene sulfonate B is the one prepared from the conventional propylene tetramer.

Percent biodegradable Alkylbenzene sulfonate A 96 Alkylbenzene sulfonate B 62 Consideration of the above example clearly demonstrates the etlicacy of the present invention.

The present invention is further exemplified by an alkylbenzene sulfonate prepared from a C olefin fraction obtained by using a catalyst system wherein the catalyst used in the first stage dimerization is the same as that described in Example I, but wherein the catalyst used in the second stage dimerization is prepared as follows: An activated carbon is impregnated with a salt of cobalt, dried and thereafter activated at a temperature of approximately 475 C. The olefin fraction was obtained by the polymerization of propylene in a first stage dimerization to form a polymer product which was separated to obtain a relatively linear dimer fraction. This relatively linear dimer fraction was subjected to polymerization in a second stage dimerization to form a second dimer fraction which was then used to alkylate benzene. The alkylbenzene so obtained was sulfonated and neutralized to obtain an alkylbenzene sulfonate. The alkylbenzene sulfonate so obtained is substantially more biodegradable than the conventional d'odecylbenzene sulfonate described in Example H hereinabove.

The present invention is further illustrated by other alkyl aromatic compounds such as naphthalenes, mixed xylenes, ortho-xylene, meta-xylene, para-xylene, ethylbenzene, methylnaphthalene, ethylnaphthalene, and dimethylnaphthalene, and particularly by the preparation of an alkyl aromatic sulfonate using as the aromatic hydrocarbon, toluene. The alkyl aromatic sulfonates so prepared are significantly more susceptible to biological decomposition than are similar conventional alkyl aromatic compounds.

What is claimed is:

1. A process for the preparation of olefin hydrocarbons suitable for the preparation of alkyl aromatic compounds susceptible to biological decomposition which comprises contacting in a first polymerization zone at elevated temperatures of from 60 C. to 350 C. and pressures of approximately atmospheric to 1000 p.s.i.g. normally gase ous mono-olefin hydrocarbons with a catalyst comprised of a crystalline zeolite molecular sieve and a metal from Group VIII of the Periodic Table, said catalyst in an oxidized stage having been subjected to at least one oxidation treatment at elevated temperatures in the presence of an oxygen-containing gas and having present from 0.2 to 15 percent by weight of the Group VIII metal calculated as the oxide of the metal, to form a polymer fraction, separating said polymer fraction to obtain a fraction comprised of relatively linear mono-olefin dimers of the normally gaseous mono-olefin hydrocarbons, said dimers having 4 to 8 carbons :atoms, contacting said relatively linear dimer fraction in a second polymerization zone at a temperature of 0 to 250 C. and a pressure of atmospheric to 2500 p.s.i.g., with an activate-d carbon supported c0- balt oxide catalyst having present from about 2 to 50 weight percent of cobalt as an oxide and having been activated in an inert atmosphere at a temperature of 400* to 575 C. to form a second polymer fraction, separating said second polymer fraction to obtain a fraction comprised of relatively linea-r mono-olefin dimers of olefin hydrocarbons in the feed to the second polymerization zone, said dimers being of 8 to 16 carbon atoms.

2. A process of claim 1 wherein the temperature in the first polymerization zone is within the range of to 235 C. and the pressure within the range of 300 to 700 p.s.i.g.

3. The process of claim 1 wherein the molecular sieve is a crystalline zeolite having a surface area of 200 to 1200 square meters per gram and pore diameters of 6 to 15 Angstroms and selected from the group consisting of alkali metallo-alumino-silicates, alkaline earth metalloalumino-silicates and alumino-silicates containing both alkali and alkaline earth metals.

4. The process of claim 1 wherein the Group VIII metal is selected from the group consisting of nickel and cobalt.

5. The process of claim 1 wherein the amount of the Group VIII metal present in the catalyst is from 0.5 to 10 percent by weight, calculated as the oxide of the metal, of the total catalyst.

6. The process of claim 1 wherein the normally gaseous mono-olefin is propylene.

7. The process of claim 1 wherein the second polymeri- 15 zation catalyst is activated in an inert atmosphere selected from the group consisting of nitrogen, propane, carbon dioxide, helium, argon, and mixtures hereof.

8. The process of claim 1 wherein the second polymerization zone is maintained at a temperature of 100 to 200 C. and at a pressure of 10 to 400 p.s.i.g.

9. The process of claim 1 wherein the amount of cohalt, as an oxide, present in the second polymerization catalyst is approximately 12 to 30 weight percent.

References Cited UNITED STATES PATENTS 16 Breck et a1. 252-455 Breck et al. 252-455 Mattox et al 252-455 Swenson et al. 260-505 Rabo et al. 260683.15 Rabo et a1. 260-683.15 Mattox et a1 260-455 Schultz et a]. 260-683.15 X Engelbrecht et al. 260-683.15 Habeshaw et a1 260-638 LEON ZITVER, Primary Examiner.

H. ROBERTS, Assistant Examiner. 

1. A PROCESS FOR THE PREPARATION OF OLEIFIN HYDROCARBONS SUITABLE FOR THE PREPARATION OF ALKYL AROMATIC COMPOUNDS SUSCEPTIBLE TO BIOLOGICAL DECOMPOSITION WHICH COMPRISES CONTACTING IN FIRST POLYMERIZATIN ZONE AT ELEVATED TEMPERATURES OF FROM 60*C. TO 350*C. AND PRESSURES OF APPROXIMATELY ATMOSPHERIC TO 1000 P.S.I.G. NORMALLY GASEOUS MONO-OLEFIN HYDROCARBONS WITH A CATALYST COMPRISED OF A CRYSTALLINE ZEOLITE MOLECULAR SIEVE AND A METAL FROM GROUP VIII OF THE PERIODIC TABLE, SAID CATALYST IN AN OXIDIZED STAGE HAVING BEEN SUBJECTED TO AT LEAST ONE OXIDATION TREATMENT AT ELEVATED TEMPERATURES IN THE PRESENCE OF AN OXYGEN-CONTAINING GAS AND HAVING PRESENT FROM 0.2 TO 15 PERCENT BY WEIGHT OF THE GROUP VIII METAL CALCULATED AS THE OXIDE OF THE METAL, TO FORM A POLYMER FRACTION, SEPARATING SAID POLYMER FRACTION TO OBTAIN A FRACTION COMPRISED OF RELATIVELY LINEAR MONO-OLEFIN DIMERS OF THE NORMALLY GASEOUS MONO-OLEFIN HYDROCARBONS, SAID DIMERS HAVING 4 TO 8 CARBONS ATOMS, CONTACTING SAID RELATIVELY LINEAR DIMER FRACTION IN A SECOND POLYMERIZATION ZONE AT A TEMPERATURE OF 0 TO 250*C. AND A PRESSURE OF ATMOSPHERIC TO 2500 P.S.I.G., WITH AN ACTIVATED CARBON SUPPORTED COBALT OXIDE CATALYST HAVING PRESENT FROM ABOUT 2 TO 50 WEIGHT PERCENT OF COBALT AS AN OXIDE AND HAVING BEEN ACTIVATED IN AN INERT ATMOSPHERE AT A TEMPERATURE OF 400 TO 575*C. TO FORM A SECOND POLYMER FRACTION, SEPARATING SAID SECOND POLYMER FRACTION TO OBTAIN A FRACTION COMPRISED OF RELATIVELY LINEAR MONO-OLEFIN DIMERS OF OLEFIN HYDROCARBONS IN THE FEED TO THE SECOND POLYMERIZATION ZONE, SAID DIMERS BEING OF 8 TO 16 CARBON ATOMS. 